A new allergy risk to a common ingredient has been identified in a recent case study that has implications for vaccination. Gelatin, often found in lunchmeats, jellies, and gummy candies, is also used in vaccines, and allergy — though rare — can trigger anaphylaxis. An allergy to egg is no longer considered a risk of flu vaccination, but investigators presenting here at the American College of Allergy, Asthma & Immunology (ACAAI) 2013 Annual Scientific Meeting warned that gelatin allergy can be a problem.It is rare, and the first case reports were published in the mid-1900s, Stephanie Albin, MD, from the Jaffe Food Allergy Institute at Mount Sinai in New York, New York, told Medscape Medical News. However, it can present significant issues because many vaccines — and foods — contain gelatin. Gelatin is a mixture of peptides and proteins produced by partial hydrolysis of collagen extracted from cow, pig, and fish, she explained. Patients with gelatin allergy do not react to meat because gelatin is derived from tendons and bones rather than the flesh. And gelatin in vaccines is more likely to cause an allergic reaction because it is concentrated, purified, and processed and has direct access to the immune system through injection.vaccines that contain gelatin include those against influenza; measles, mumps, and rubella (MMR); varicella; yellow fever; zoster; rabies; Japanese encephalitis; and diphtheria, tetanus, and pertussis (DTaP).Source: American College of Allergy, Asthma & Immunology (ACAAI) 2013 Annual Scientific Meeting. Abstract P104. Presented November 9, 2013.